Sound box



T. C. ROBERTS ET SDU im BOX Filed Aug. 18, 1921 Patented .luly l, 1924.

THEODORE C. ROBERTS, OF NEW YORK, N. Y., AND FRANK C. HINCKLEY, OF STRAT- FORD, CONNECTICUT, ASSIGNORS, BY MESNE ASSIGNMENTS, TO COLUMBIA PHONO- GRAPH COMPANY, INC., A CORPORATION OF NEW YORK.

\ SOUND BOX.

Application filed August 18, 1921. Serial No. 493,218.

10 all whom t may concern.'

Be it known that we, Trruononn C. Ronn'rs and FRANK C. HINCKLEY, citizens of the United States, and residing, respectively, in the city of New York, county and State of New York, and Stratford, county of Fairfield, State of Connecticut, have invented certain new and useful Improvements in Sound Boxes7 of which the following, taken in connection with the accompanying drawings, is a specification.

rlhis invention relates to an improved sound-box which can be used for sound recording, but is particularly suited for sound-reproducing machines. It has for its primary object the production of a soundbox in which an accurate reproduction of recorded sounds will be produced with iidelity to the original quality, pitch, and volume; and in which extraneous vibrations and other detrimental influences usually experienced in the mechanical reproduction of sound, are eliminated. Heretofore, these deficiences have been met-to an extent-by compromise, so that while a true reproduction of all kinds of musical sounds was never possible, the reproduction of certain qualities of sound was brought to a more or less perfect state; while on the other hand, other sound qualities were sacrificed. In other words, the reproduction was attuned to a certain class of reproduction and could, therefore, only imperfectly reproduce other classes. This invention contemplates the perfect reproduction of all qualities of sound, and to this end, its various elements are so co-ordinated as to produce a. soundboX of true universality.

An important feature of the invent-ion is the pivotal mounting of the needle-arm in such a manner as to permit the greatest freedom of action; and which also permits adjustment to such accuracy as to practically eliminate all lost motion and looseness.

It is also an object to provide a soundbox in which wear at the pivot is reduced to a negligible quantity, and which permits adjustments to certain pre-determined standards by mere a-ssembling of the parts, and without dependence upon the skill or judgment of the assembler.

A further object is to provide a soundbox adapted to economical manufacturing methods, and which, while having the accurate adjustments and delicate functional characteristics of a fine precision instrument, will at the same time be of sturdy construction, and capable of manufacture and assemblage in quantity, and by relatively unskilled workers.

A still vfurther object is to so inclose the parts as to protect them from dust, and prevent their being tampered with, or deranged, through handling.

W ith these and other objects in View, an embodiment of the invention is disclosed in the accompanying drawings, and will be hereinafter more fully described with reference thereto, and, finally, the invention pointed out in claims.

In the drawings- Fig. l is a perspective view of the completely-assembled sound-box, according to the present disclosure.

Fig. 2 is. an extended perspective view showing the several parts separated.

Fig. 3 is a central vertical sectional view of the sound-box, shown partly in elevation.

Fig. fi is a fragmentary front View of the lower portion of the sound-box, shown partly in elevation and partly in section, and with the cover plate partially broken away, to disclose the constructional details.

Fig. 5 is a sectional detail view taken along the line 5-5 of Fig. 4, and showing the arrangement of the upper knife edges of the pivotal support.

Fig. 6 is a sectional detail view taken along the line 6-6 of Fig. 4, and showing the arrangement of the lower knife edges of the pivotal support.

Fig. 7 is a vertical semi-sectional view of the needle-arm structure.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings.

Referring to the drawings, the sound-box according to this invention comprises a casing 10, Fig. 8, having a central tubular projection 1l for attachment to the tone-arm, and provided with an integral marginal flange 1Q, Fig. 2, projecting slightly beyond the periphery of the back portion of the casing and being knurled. The back portion is of unbroken circular outline, while the flange is cut away at its lower portion to provide flats 13 and 14, at each side of an intermediate gap 15, and disposed at right angles to the projection 1G of the back portion. An annular groove 17 is formed adjacent the inner periphery of the flange to accommodate one of the diaphragm-retaining gaskets. The casing may preferably be a die casting of die cast metal, but it will be understood that it may also be formed in other ways, and of other materials-as, for instance, of steel or brass, either cast, turned, or wrought; and it may, if desired, be constructed of two picces,-that is, the flange may be in the form of a ring secured to a separate back portion.

The diaphragm-retaining ring 18 is of corresponding exterior diameter to the back portion of the casing so as to give to the sound box a symmetrical appearance, as shown in Fig. 3, while its inner diameter is less than that of the inner diameter of the flange 12 and so projects inwardly over the upper tubular rubber gasket 19. lletween the upper gasket 19, Fig. 3, and the lower gasket 20, which latter is disposed in the groove 17, the diaphragm 22 is held with its edge spaced from the flange 12, as shown in Fig. G, or it may be in contact therewith, as shown in Fig. 5. The retaining ring 18, Fig. 1, is secured upon the flange 12 by screws 21 equally spaced apart, around the ring, the dimensions of the ring, the flange, the diaphragm, and the gaskets being such, that when the ring 18 is tightly engaged with the upper surface of' Athe flange 12, the diaphragm is properly positioned and is held with the desired degree of pressure. The amount of pressure is such that the diaphragm will neither be held so tight as to produce binding strain upon itresulting in diminished reproduction-nor so looseas to allow of any blasting This relation of parts is also utilized, as will presently appear, in securing the proper adjustment of the needle-arm bearing. At its lower portion, the retaining ring is provided with an inverted T-shaped opening 23 extending` through its inner edge, to form a slot. and below this opening it is extended into a projecting resilient apron portion having spaced leges 24 and 25, Fig. 2, bent inwardly substantially at right angles from its lower straight edge, the apron portion being substantially spaced, when assembled, from the flats 13 and 14 of the casing.

Upon the flats 13 and 14 there are secured rectangular block portions 26 and 27 provided at the ends of a spacing and coupling or truss plate 28 formed integral rtherewith. The plate portion is secured to the projection 16 of the casing by screws 29 and 30, Fig. 4, and the block portions to the flats 13 and 14 by screws 31 and 32, thereby forming a rigidly connected structure.

Upon the under surfaces of the blocks 26 and 27 and adjacent the inner edges thereof, there are formed projecting V-shaped knifeedge-s 33 and 34 having an angular-ity, for instance, of about 90 degrees-as shown in Fig. -and having their edges disposed in a straight line at right angles to a line passing through the center of the diaphragm and along the axial line of the needle-arm; and being also disposed in the central vertical plane of the diaphragm. The part or unit comprising the block portions 26 and 27, and the coupling plate 28, Fig. 2, is preferably formed of steel and arranged to be shaped by suitable blanking and milling operations, and on a quantity production basis.

rlhe ledge or apron portions 24 and 25 of the retaining ring 18 are provided upon their inner sides with blocks or nuts 35 and 3G, soldered in place along their under and side surfaces contacting with the retaining ring and ledge surfaces, and having vertically disposed screw-threaded passages 37 and 38, Fig. 4, extending therethrough and through the ledges. lVithin these passages there are disposed screws 39 and 40 having their axes disposed in the central vertical plane of the diaphragm, and adapted to have their inner ends, which are flattened to form bearing seats, as shown in Fig. 6, adjusted so that they will be in the line of the knife-edges 33 and 34. These screws are intermediately disposed in respect to the knife-edges 33 and 34, and are equally spaced therefrom.

These screws are provided at their exposed ends with kerfs 41 and 42 for engagement by a screw-driver. They have retaining lock-nuts 43 and 44 screwed thereon and bearing upon the under sides of the ledges so as to fix the position of the screws when they are properly adjusted. The apron structure of the retaining ring, while substantially rigid, permits of a slight resilient movement of the ledges, due to the resiliency of the metal at the bend of the apron, as shown in Fig. 6.

Between the bearings formed by the knife-edges 33 and 34 and the upper ends of the screws 39 and 40, the oscillating needle-arm structure is pivotally mounted. The needle-arm structure comprises a` needle-arm supporting bar or bridge having a transverse intermediate portion 45, Fig.v 2, and end portions 46 and 47 bent downwardly therefrom and disposed in parallel relation thereto;-the intermediate portion being provided medially with a forwardly extending projection 48 and a rearwardly extending hump 49,-the latter to provide sufficient surrounding metal for securing the needle-holder in place. lVhen assembled, this hump portion 49 projects into a cutout 50 of the plate 28. The needle-holder 51 has a reduced stud 52, Fig. 7, formed at its end which is inserted into an opening 53 formed centrally of the bar and rigidly secured, as by riveting, spot-welding, or other like means. It will, of course, be understood that this and the other details ot construction, described with particularity, is illustrative only and not limiting.

A socket 54, Fig. 7, formed in the needleholde-r, has triangulated grooves 55 formed therein. At the forward side of the needleholder, there is provided a boss 56 having a screw-threaded passage extending therethrough, in whichv a needle-retaining thumbscrew 57, Fig. 2, is disposed, its end bearing upon a stylus or needle inserted in the socket to removably but rigidly secure it in place; this being the usual construction.

The needle-arm 58 is truss-shaped, and is provided at its lower enlarged end with a stud 59, Fig. 7, inserted in a rectangular hole G0 formed .in the needle-arm support, and rigidly secured thereto by riveting, spot welding, or other means, and in such manner that a substantiallyintegral structure is produced. The upper end of the needlearm is bent inwardly, as at 61, and has a fiat head 62 formed thereon, and provided with a threaded central aperture 63 coincident with a central aperture 64, Fig. 3, in the diaphragm. The needle-arm head 62 is secured to the diaphragm by means of a screw 65, projecting through from the connection or back side of the casing, and having a washer 66, preferably of brass, disposed between its head and the inner surace of the diaphragm.

The arrangement of the needle-holder is such, that the needle held therein will have its point in the central plane of the diaphragm, and in a line at right angles to the transverse needle-arm support and passing through the center of the diaphragm.

The end portions 46 and 47, Fig. 2, of the needle-arm support, are provided with V- section grooves 67 and 68 open at their outer ends and having abutment shoulders, as at 70, at their inner ends-their angularity being substantially greater than the knifeedges 33 and 34 with which they cooperate, as shown in Fig. 5. The abutment shoulders are so spaced as to substantially centralize the needle-arm, and at the same time, allow suiiicient clearance with respect to the inner ends of the knife-edge portions 33 and 34 to prevent frictional contact.

Upon the under side of the intermediate portion 45, Fig. 4, of the needle-arm support there are provided knife-edges 7l and 72 having, for instance, an angularity of substantially 90 degrees and adapted to rest upon the ybearing-seats at the ends of the screws 39 and 40. This is shown in detail in Fig. 6. These knife-edges 71 and Y2-as also the apices of the grooves 67 and 68, Fig.

4,--are disposed along the transverse line of the knife-edges 33 and 34. The slight resiliency of the ledges 24 and 25 permits the screws 39 and 40 to be adjusted with the greatest delicacy to produce the proper retention 0f the parts against looseness, and at the same time, to permit of unrestricted pivotal action of the needle-arm structure. Also, wear upon the parts, will be automatically taken up by this resiliency. 1t may, too, of course, be taken up manually by slight adjustment of the screws; however, the wear even over a long period of use would probably be too negligible to require this adjustment.

The retaining ring 18, through its tight engagement with the {iange surface, precisely positions the diaphragm in a true parallel plane in respect to the casing, and at the same time, all parts are so formed and assembled as to cause a coincidence of the central plane of the diaphragm with the pivotal aXis of the needle-arm bearings. The transverse axis of rotation of the needle-arm structure is in a line at right angles to a line passing through the center of the diaphragm and the needle point. And the needle point is also in the central plane of the diaphragm. Thus, a perfect leverage condition is produced, and the needlearm functions with the least Jrictional resistance and the greatest insurance against wear, looseness, or derangement of the parts. The structure is not only compensating, but at the same time is entirely. free of springs or other loose or independently movable parts which, through their natural vibration periods, would set up vibrations foreign to the recorded vibrations of the record, and injurious to a perfect reproduction.

There is still one feature to be described, which accounts for the very remarkable results obtained with this reproducer in actual use.

The various details of construction, including a constantly tight pivotal support for the needle-arm, and yet a support free of all' binding action thereon, and the accurate positioning of the diaphragm between its gaskets, under a certain pressure, have, no doubt, much to do with the noticeable improvement in reproductive qualities of the sound-box embodying this invention.

However. a feature of greatest importance is the careful designing 0i' each and every part which makes up the device, so that the composite period of vibration of the entire assemblage will be an amount equal to the average period of vibration of sounds to be reproduced in it. The inventors have discovered that each and every part composing the sound-box is directly or indirectly .set into vibration during the playing of the phonograph; and that each such part acting, as it does, in conjunction with other parts of the reproducer, gives a joint period of vibration; and that these Various joint periods finally combine and make a resultant period of vibration of the completely assembled reproducer.

Thus, a reproduoer can be made by the careful proportioning of its parts, so that it Will have a composite period of-say-300 vibrations per second. It has been found that with a reproducer having this period, those records, the average sound in which is around 300 vibrations per second, are reproduced far more naturally and with much greater brillianoy than is obtained in a reproducer having a Widely different period of vibration. For, in the first case, the vibrations set up in the reproducer itself, are in sympathy with the sounds being reproduced therein, and so instead of causing confusion in the reproduction, actually amplify and clarify it; While in the latter case, (as for instance, in using this same reproducer in a violin solo record, Where the average pitch of the sounds in the record is as much as 900 or 1,000 per second), this diaphragm Would be far too sluggish in action, and out of sympathy With the high pitched sounds. Consequently, much of the detail would be lost.

These facts being so, the problem in developing this invention has been to provide a sound-box for universal use in which the vibration period is approximately equal to the average vibration period of the average record played. This is accomplished by so designing all of the parts, as above pointed out, With relation to each other, that their `joint periods of vibration combine and produce a resultant period, this period being that which is computed to be the desired average; and it is this which is largely responsible for the remarkable and superior results obtained by this sound-box.

lVhile there has been illustrated and described a preferred and satisfactory embodiment of my invention, it is obvious that changes may be made therein Within the spirit and scope thereof, as defined in the appended claims.

Having now described the invention, what is claimed as new, and for which Letters Patent is desired, is:

1. A sound-box comprising a body member having laterally disposed spaced p0rtions providing a gap between them, bearing members removably mounted on the portions and being xed and non-adjustable With relation to each other When mounted on said portions and when removed therefrom, a stylus lever, a cross-bar carried by the stylus lever and pivotally bearing upon the bearing members at its ends, and means adapted to maintain the cross-bar in engagement with the bearing members.

2. A sound-box comprising a body member having laterally disposed portions providing a gap between them, bearing members removably mounted on the portions and being fixed and non-adjustable with relation to each other when mounted on said portions and when removed therefrom, a stylus lever extending into the gap, a cross-bar carried by the stylus lever and having its end portions olf-set to engage the bearing inembers, and means adapted to maintain the cross-bar in engagement With the bearing members.

Signed at Bridgeport, in the county of Fairlield and State of Connecticut, this 20th day of July, A. D. 1921.

THEODORE C. ROBERTS. FRANK C. HINCKLEY. 

